钆掺杂氧化锌薄膜和器件的性质研究

发布时间：2018-01-31 13:59

本文关键词： YZO YIZO 透明导电薄膜薄膜晶体管磁控溅射法　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：氧化锌(ZnO, Zinc oxide)是一种新型的Ⅱ-Ⅵ族宽带隙半导体材料,禁带宽度为3.37eV,室温下的激子束缚能为60meV。以ZnO为基底掺入稀土金属钇(Y, yttrium)可以使薄膜材料带隙展宽,光透过率提高,电阻率降低,紫外辐射增强。国内外有关YZO的研究起步较早但进展缓慢,目前还处于实验室研究阶段,尚未见有关其在商业应用中的报道,这说明Y掺杂ZnO薄膜的结构和光电特性还不能满足实际应用的需要。因此,寻找薄膜的最佳制备条件,进一步优化薄膜特性,对其在太阳能电池、薄膜晶体管等光电器件领域的应用具有重大意义。针对ZnO的Y掺杂,本论文共研究了两种材料,即：Y掺杂ZnO (YZO)和钇铟(In, Indium)共掺杂ZnO (YIZO)。1.YZO透明导电薄膜本论文采用射频磁控溅射法,室温下在钠钙玻璃衬底上制备了YZO透明导电薄膜。通过改变溅射时间,溅射功率,溅射气压等制备条件,研究了不同生长条件对薄膜结构、形貌、光学和电学特性的影响。主要研究内容及结论如下：(1)研究了薄膜厚度(溅射时间)对YZO薄膜结构、形貌和光电特性的影响。薄膜厚度分别为0.98μm、1.70μm、2.04μm和2.52μm,分别对应溅射时间30min、40min、50min和60min。通过对薄膜进行XRD、AFM、紫外-可见光分光光度及霍尔效应的测试和数据分析,发现所有薄膜均为六角纤锌矿型结构。随着薄膜厚度的增加晶粒尺寸逐渐增大；薄膜在可见光区的平均透过率均超过80%；光学带隙由3.270eV逐渐减小至3.225eV；薄膜电阻率先减小后增大。薄膜厚度为1.70μm时电阻率最低,其值为8.13×10-3Ω·cm。(2)研究了溅射功率对YZO薄膜结构、形貌和光电特性的影响。溅射功率分别80W,100W,120W和140W。通过对薄膜进行XRD、AFM、紫外-可见光分光光度及霍尔效应的测试和数据分析,发现所有薄膜均为六角纤锌矿型结构。随着溅射功率的增加,晶粒尺寸先增大后减小；可见光区平均透过率超过80%,带隙逐渐增大,分别为3.24 eV、3.26 eV、3.27 eV和3.28 eV,带隙的变化可以用Burstein-Moss效应来解释；电阻率先减小后增大,溅射功率为100W时薄膜电阻率最低,其值为9.01×10-4Ω·cm。(3)研究了溅射气压对YZO薄膜结构和光电特性的影响。溅射气压分别1.0Pa,1.4Pa和1.8Pa。通过对薄膜进行XRD、AFM、紫外-可见光分光光度及霍尔效应的测试和数据分析,发现所有薄膜均为六角纤锌矿型结构。随着溅射气压的增加,衍射峰半高宽增大,相应的晶粒尺寸减小,薄膜结晶质量变差；带隙略有增大,可以用Burstein-Moss效应来解释；电阻率显著增加,1.0Pa时获得最低电阻率1.503×10-3 Q·cm,带隙为3.26 eV。2. YIZO透明导电薄膜和TFT(1)采用磁控溅射法制备了YIZO透明导电薄膜,重点分析比较了不同厚度YIZO薄膜的结构、形貌和光电特性的差异。研究发现,室温下制备的所有YIZO薄膜均为非晶结构,可见光区的平均透过率均超过83%。薄膜厚度对带隙影响不大,所有薄膜带隙均为4.18eV。(2)在薄膜研究的基础上,以重掺杂的P型硅为栅电极,以YIZO薄膜为有源层,以金属铝为源漏电极,制备了底栅顶接触结构的YIZO薄膜晶体管(YIZOTFT),并研究了不同有源层厚度对器件的输出和转移特性的影响。(3)所有YIZO TFT均为n沟道耗尽型器件,所有样品都表现出了良好的夹断特性。随着YIZO层厚度的增加,器件的阈值电压逐渐向负电压方向漂移,迁移率和开关电流比均迅速减小,亚阈值摆幅逐渐增大,器件性能变差。有源层厚度为20nm的器件的开关电流比超过105,亚阈值摆幅为2.20 V/decade,阈值电压为-1.0V饱和迁移率为0.57 cm2/V·s。
[Abstract]:Zinc Oxide (ZnO Zinc oxide) is a new type of II-VI wide band gap semiconductor material, the band gap is 3.37eV at room temperature, the exciton binding energy of 60meV. with ZnO as substrate is doped with rare earth yttrium metal (Y, yttrium) can make the film band gap broadening, the transmittance is improved, the decrease of resistivity and enhanced UV-B radiation. The domestic and foreign research on YZO started earlier but slow progress is still in the stage of laboratory research, has not yet been reported in the relevant business applications, the structure and properties of Y doped ZnO thin films can not satisfy the need of practical application. Therefore, the optimum preparation conditions for thin films. To further optimize the thin film properties, the solar cell has the significance of the application of thin film transistor devices. For ZnO doped Y, this thesis studies two kinds of materials, namely: Y doped ZnO (YZO) and yttrium indium (In, Indi UM) ZnO (YIZO) Co doped.1.YZO transparent conductive film by the RF magnetron sputtering, YZO transparent conductive films were prepared at room temperature in the sodium calcium glass substrates. By changing the sputtering time, sputtering power, sputtering pressure and other preparation conditions, studied the morphology of different growth conditions on film structure, optical effect and the electrical properties. The main research contents and conclusions are as follows: (1) the study of film thickness (the deposition time) on YZO thin film structure, morphology and photoelectric properties. The film thickness is 0.98 m, 1.70 m, 2.04 m and 2.52 m, respectively, corresponding to 30min 40min 50min, the sputtering time. Through XRD and 60min., on AFM film, visible spectrophotometry and Holzer effect test and data analysis of UV, found that all films were all six corners of the wurtzite structure. With the increase in film thickness the average grain size increases; thin film in the visible light region. The average transmittance of more than 80%; the optical band gap decreases from 3.270eV to 3.225eV; the thin film resistor first decreases and then increases. The film thickness is 1.70 m when the lowest resistivity, its value is 8.13 x 10-3. Cm. (2) of the sputtering power on YZO thin film structure, morphology and optical properties of the influence of sputtering power. 80W, 100W, 120W and 140W. by XRD on AFM film, visible spectrophotometry and Holzer effect test and data analysis of UV, found that all films were all six corners of the wurtzite structure. With the increase of sputtering power, the grain size increases first and then decreases; average visible transmittance more than 80%, the band gap increases, respectively 3.24 eV, 3.26 eV, 3.27 eV and 3.28 eV, the change of the band gap can be used to explain the Burstein-Moss effect; resistance first decreases and then increases, the sputtering power of 100W thin film resistivity minimum, its value is 9.01 * 10-4. Cm. . (3) studied the effects of sputtering pressure on the structure and photoelectric properties of YZO films. The sputtering pressure were 1.0Pa, 1.4Pa and 1.8Pa. by XRD on AFM film, visible spectrophotometry and Holzer effect test and data analysis of UV, found that all films were all six corners of the wurtzite structure. With the increase of sputtering pressure, the diffraction peak width increases, the grain size decrease, the crystal quality of the films became worse; the band gap increases slightly, can be used to explain the Burstein-Moss effect; resistivity increased significantly, 1.0Pa get the lowest resistivity 1.503 * 10-3 Q cm 3.26 eV.2. band gap of YIZO films and TFT (1) YIZO transparent conductive thin films prepared by magnetron sputtering method, based on the analysis of the structure of YIZO films with different thickness, different morphology and photoelectric properties. The study found that, at room temperature for all the YIZO films are amorphous structure, visible The region average transmittance of more than 83%. film thickness has little influence on the band gap, the band gap of all the films are 4.18eV. (2) on the basis of film studies, P type heavily doped silicon as the gate electrode with YIZO film as the active layer, based on aluminum source drain electrode, preparation of the bottom gate the top of the YIZO thin film transistor contact structure (YIZOTFT), and the effects of different active layer thickness on the device output and transfer characteristics were studied. (3) all YIZO TFT are N channel depletion mode devices, all the samples showed good pinch off characteristics. With the increase of the thickness of YIZO, threshold voltage the device gradually to the negative direction of voltage drift mobility and on-off current ratio were decreased rapidly, the subthreshold swing increases gradually and the performance of the device gets worse. The thickness of the active layer of 20nm device switch current is more than 105, sub threshold swing is 2.20 V/decade, the threshold voltage for -1.0V saturation transfer The rate is 0.57 cm2/V. S.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.25

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